Added hello_world counter example to check if wiki / README are outdated

Author: fschutt

azul/Cargo.toml

@@ -81,6 +81,12 @@ name = "game_of_life"
 path = "../examples/game_of_life/game_of_life.rs"
 required-features = []
 
+[[example]]
+name = "hello_world"
+path = "../examples/hello_world/hello_world.rs"
+required-features = []
+
+
 [[example]]
 name = "hot_reload"
 path = "../examples/hot_reload/hot_reload.rs"

examples/README.md

@@ -23,6 +23,10 @@
 - Shows how to use timers in order to update the game board every 200ms.
 - Performance demo, performs the layout for 5600 rectangles (TODO: Should be replaced by an image).
 
+## `hello_world`
+
+- Hello World "counter" example, used for checking that the README and the wiki aren't out-of-date.
+
 ## `hot_reload`
 
 - Shows a window where the CSS can be hot-reloaded (you can run the demo, then edit the )

examples/hello_world/hello_world.rs

@@ -0,0 +1,30 @@
+extern crate azul;
+
+use azul::{prelude::*, widgets::{label::Label, button::Button}};
+
+struct DataModel {
+  counter: usize,
+}
+
+impl Layout for DataModel {
+    fn layout(&self, _info: LayoutInfo<Self>) -> Dom<Self> {
+        let label = Label::new(format!("{}", self.counter)).dom();
+        let button = Button::with_label("Update counter").dom()
+            .with_callback(On::MouseUp, Callback(update_counter));
+
+        Dom::div()
+            .with_child(label)
+            .with_child(button)
+    }
+}
+
+fn update_counter(app_state: &mut AppState<DataModel>, _: &mut CallbackInfo<DataModel>) -> UpdateScreen {
+    app_state.data.modify(|state| state.counter += 1)?;
+    Redraw
+}
+
+fn main() {
+    let mut app = App::new(DataModel { counter: 0 }, AppConfig::default()).unwrap();
+    let window = app.create_window(WindowCreateOptions::default(), css::native()).unwrap();
+    app.run(window).unwrap();
+}